Recovery of spent treating reagents



Sept. 12, 1933. B. F. DooLEY. JR

RECOVERY OF' SPENT TREATlNG REAGENTS Filed Sept. 24, 1930 Ill,

RECOVERY 0F SPENT `trmrli'lrllvcf 'Y `Byron F. Dooley, Jr., 'PortArthun` Tex.",.assignor; Y to `The Texas- Company, NewYork, N.,Y., a l* 1 corporation of Delaware f A'plvilcation September 124; 1930 Serial ANof 484,152.

` 1.11 Ciims Y inventionjrelates tofthe recovery of valuable'products from spentftreating reagents in petroleum" refineries, and morev particularly in- ICH volvesthe recovery of valuable'conipounds from thelead sludgeY Whichresults from vthe, treatment Y of .certain petroleum distillatesA with sodium plumbiteff L j Y L carrying out my invention, I take advantage fjthesusceptibility of thelead sludge to undergoic'ertain chemicalchanges'when exposed to the atmospherejQBy weathering the sludge in a] suitable manner, I am able toconvert V.the lead compounds toa form"tliat can be. dissolved or.

suspended in aqueous caustic soda andreused'as a treating reagent .for petroleum oils..

1 Most petroleum uistulates, f @spatially the lighter fractions,` such as gasoline,-naphtha and kerosenecontain sulphur compounds, which give them aV disagreeableodorfand renders themun- VsuitableV for market. ,Thesefcompounds' are re-V The sludge 'produced' in the manner indicated fabove "was formerlysettledk from the caustic liquor and; run to theseweror otherwise disposed of as a"'vvajster'product*in4 themost convenient nam'ierL As a' result,'.the*lead contentoifVV the sludge was Tacomplete loss which increased the A treating-'feest and f reflected-.- in the price'ofi `the linishedproducts .More .recently several methods have .'been' developed fcrsthe'recovery of this sludgejfromgspent doctor..V -The-.-{details of the different methods. will nota bev given, but :it Ymay be mentioned that they consist fundamentally ofl All of theseV inherentlyV Ya result of*Y natural =agencies, .the cost is practicallynil. d

' More particularly, in accordance Awith my invention, a lightl petroleum" oil is treatedv with sodium plumbiteto sweetenthe oil and precipitate lead sludge in the spent solution.v The sludge is then separated frornthe` spent solution anddelivered .to`a weathering pito'r basin inl-the ground.

Asfthe sludge weathers, the lead'compoundsare converted Yinto compounds soluble in alkali, and

the insoluble compoundsare'changed to a `granular form.l The soluble compounds are dissolved in caustic alkali and the solution reused 'as a doctor solution or thesoluble compounds may be disfsolv'e'dQfthe solution decanted and the insoluble granular.materialffsuSpendedfin caustic soda to bei used asia treating agent.

I Areactioon has been `found to spontaneously set Y. fin-Whenthe sludgeoeisrrexposed to sunlight and varyingweatherconditions, which proceeds more orless rapidly, depending on conditions. Without .gongv into VVthe. theory` of-the reaction that takes placevasthe solution is exposed to theatmosphere,4 it is sufficient to say.l that it is thought to involve primarily autoxidation ofthe lead sul- Vpl'iide to 'oxygenated'compounds Consistent'with this suggestion `of the typepof reaction, it has been noted Vthat some; instances sunlight `is very de- 'siraloleV -Another -favorable condition is a finely precipitated.sludgeprwhereby large exposed surfaces areproduced.; `It has also been suggested that certainreaction productsrwh'ich are absorbed by; the sludge during-the sweetening operation may vbe important to the success of the reaction. `Whilethe reaction may-be satisfactorilyrealizedy in earthen ,pits, I Ahave Valso 1 found it to* .be

ofconsiderable advantage to., employ shallowpans Y into which theysludge, together with sucientof the spent solution or liquor to form arslurry, may be disposed `and subjected Vto weathering with occasional or slow continuous stirring. When weathering the sludge in this way in the presence of a small amount ,of thel expended caustic conthe sludge may be converted into the soluble form. d

.The presence'of the liquor appears to exercisefa catalytic*effect upon the reaction whereby the reactionnrateiis approximately double :that ordi- Leo . it is apparent that the process may be continuous,

n for -whle no definite amount mustnecessarilybe but vthis islnotja disadvantage, since often'theinexposed narily occurring in an earthen pit during the :same period ofjtime,V k l j ,Y Y .l

A'liquid Vtight pan isy of course offurther advantage in thatit avoids the, otherwise Washing away and soakage of some of 'the valuable-,materials into th'efground.

The 4time required for a substantial conyersion of thesludge yWill necessarily vary, since the ,weather conditions are not constant. YIt vis not- `so extensive, however, as to. Acause .,diculty. Thus, yduring a period of one inonths'exposurev in anrearthen pit as much as 20 percent, oi" the sludge has been convertedto` compounds soluble in caustic. 'Y a ln-reneries where large'quantities oiflithargen l are consumed inthe sweetening operatiomacon siderablev lake of,y sludge may accumulatafand,

after a considerablesupply has once accumulated,'k

converted, Ayet inf large deposits, a sufcient time would be insured to producethedesired results.'

, "Thequantity jofitheweathered sludge to producea sweeteningreagentdepends onthe degree kof conversion@ jln large deposits where theY time of exposure hasbeen extensive, it has beenofound thatil tor 20 pounds` of .theA sludge vper barrel of. alkali'producesa satisfactory sweetening reagent l when thev sludge was dissolvedinleeZOi Bfcaustic. The sludge'ordinarily is vo nly'paa'tly soluble,

soluble portionof the sludge is desirable` as a suspension in the's'olution to aildjin theysweetening sreaction." YIt* is therefore practicalftolutilize the entire sludge whenf-the soluble portion' is relatively'flarge; In case-the vpercentage of soluble compounds is' low,V the insoluble'rnaterial 'may be separated from the new solutionandiagain `re- .Y turned to the weathering p itorused as al suspen-y sionfijn'V caustic *as previously7 mentioned; Y

The spentdoct'or solution and sludge'frorn the Aagitators previously mentioned',v are delivered'V to a separatingtank Where the sludge I naylce'settled orV 'otherwise conveniently separated from the Vspent 'doctor' liquor and .the latter drawn off.V

The'sludgawhichmay bevs'emi-dry or 'a' con centrated suspension, 'maybe treated vinfvarious modes. Accordingto one'modicatiomthe sludge 'is delivered to; a weathering basin; -Thisl'basin compounds andfg'ranular insoluble-material yis 1 delivered to amak'e-up'tank No.='1,where"itV is mixed witha solution vof caustic soda! 'I he'causf tic-'alkali dissolves th'soluble compounds, leaving thegranular'fmaterial ifsuspension. The vsuspended granularrnaterial is' settled'in a set-'- tling tanleandfthel clear solution decanted.Y The latter'isthenl deliveredto Ythe doctor solution i tank to be' 'used inr the sweeteni'ng 'agitatorsl {Thegranula'r' insolublematerialn is passed to'a make-up tankV N o f Y2, 'where it' isVV vsi'ispended -in o aqueous' caustic soda of yabout 10 to 20 Baume,

preferably'lS Baume. The 'suspension iscon# I i ducted to sweetening agitators and there agitated withthe oil tob'e sweetened;A` If `desired', 'airvrnay be used in these agitators as disclosed'V in the U. S. patentv ,to Rowsey, No. 1,754,649; vgranted[April 15,*1931').v It is preferable insweetening with such suspension of sludge 'in caustic fto `Itreat an-- oil.

vvlic'hjis4` to" be further refined, forA example a naphtha that is to be redistilled. This 'isbecause a loss in 'colorisoften 'experienced during the sweetening operation. of

l The sweet naphtha and spent sweetening agent are separated and Withdrawn from theagitators to` be disposed of 'as desired," Preferably, this spent sweetening agent' is again returned to the separating'tank and from thence to the Weathering basin, thecycle being `repeated indenitely. According toY another modification of vmy process, .the sludge from the separating tank .i previously mentioned maybe delivered Whole or in part to a makefup tank No. 3 as indicated on the chart..- Invthis tank the sludge is suspended in",Y caustic lsoda, but'L 1 usually this suspension,l

either from the'linited quantity or the nature of o additonalusupply of sludgeY from the weathering basin-where a considerable deposit is ordinarily kept. The resulting vsuspension:in make-up tank No. 3 isthen delivered tothenaphthasweetening 'aeitators andl used iny a similar manner' as the suspension 'ofv granular Ysludge heretofore described? i, A .i

Obviouslyfvfromthe nature.'4 'of' process,

many variations and modifications are possible.k

While y`I vhave ldescribed a methodof carrying out theproce'ss in a" somewhat particular mannerLI doY nctwishto limitmyseli tothe details itlfrlerejn specied.` It will, thereforafbe understood that onlysuehjlimitations' are to be imposedas linclicated by the following claims.

1;V A processof-treating lead sludge from spent doctor solutions which.comprisesseparating the lead sludge from v,thesp'ent sdocto'rjsolution; eX- posing saidfsludge to the ,airl under atmospheric conditions forfsulrioient time to produce-a weathf ered vsludge containing a fsubstantvialV amount of lead: compounds 'soluble vin alkali; and'dissolvin'g thesoluble "colnp'ounds` in caustic alkali toorin a doctor solution suitable for treatinglight pe# troleurn oils'.` l n s' 2V. A process of treating lead sludge from spent doctor solutions 'which comprises separating, the lead lsludge from the spentjdoctor solution and collecting said sludge in a` shallowl lake, exposing the surfacerof said lake to 'Weather conditions 'for at least a month to" producev a weatheredsludge containing lead compounds soluble 'in alkali,y and v thelsludge,is not satisfactory as a sweetening mixingtheweathered sludge'with caustic/alkali v tolforrn a mixture suitablefor sweetening light petroleum oilspj.`

3. A processV ."of fr trerating. [lead 'sludge' from 130 spent doctor solutions Ywhich ccvwmprises separat,- Vi/ng'the lead fsludgelfrom' the spent vdoctor solu- .tion'andcollecting ysaid sludgein the forrn'of a slurry ina shallow body, exposing said body -to airand sunlight under atmospheric conditions of temperature and4 pressure for a suicient time to produce a weathered-.-sludge containingv 'a substantialamount-'of compounds soluble in alkaliA Sand dissolvi g'fthe"solublev compounds 1in vcaustic soda'."'= s v,

4; A'processof treating lead sludge from spent `doctor solutions'lwhi'ch comprises separating `the lead"sludg`effrorn the'spentgdoctor solution and 'depositing said sludge Yin an earthen basin, main- Vtainingva"substantial bodyof sludge inisaid basin, exposing said body Vto theatmosphere,for'several vmonths 'to weatherfthe sludge andproduce soluble lead compounds, .withdrawing the 'weathered product fromfthe'basin andvmxing Athe with;

drawn material lin 1`(V)'tov20 Baume caustic soda to form a mixture for sweetening hydrocarbon oils.

5. A process for recovery of valuable products from spent doctor solutions resulting'from the treatment of-hydrocarbon oils which comprises separating the spent doctor solution containing suspended sludge from the treated oil, settling 'the sludge from the spent doctor solution, de-

canting the spent doctor solution, exposing said sludge to theV action 'of sunlight Vand varying Weather conditions for a vperiod of time sufficient to produce a weathered sludge containing a substantial amount of alkali soluble lead compounds, and mixing said weathered sludge with caustic alkali to form a mixture for treating 'hydrocarbon oils.` Y i V6.' A process for recovery of -valuablerproducts from spent doctor solutions resulting vfrom the treatment of hydrocarbonroils which comprises separating the spent doctorsolutions containing suspended sludge'from the treated oil, vsettling the sludge fromthe spent doctor solution,de

canting the spent doctor solution` and exposing a portion of the sludge tothe action of sunlight *of said sludge,v and adding weathered sludge and varying weather conditions for a period of time suicient to produce a weathered lsludge containinga substantial amount of soluble lead compounds,adding causticalkali to the remainder to the mixture of unweathered sludge and caustic alkali to form a mixture for treating hydrocarbon oils.

' 7. A process for recovery of valuablevproducts from spent doctor .solutions resulting fromAthe treatment of hydrocarbonoils which comprises separating 4the sludge from the spent. solution,

1 weathered sludge containing a weathering said sludge by exposure to sunlight and weather conditions for a Vsufficient time to convert `alkali insoluble lead compounds to a substantial amount of alkali soluble compounds yand an insoluble portion, dissolving the soluble compounds in caustic alkali to produce a doctor` solution for treating hydrocarbon oils, and separating the insoluble portion'of the Weathered sludge from said doctor solution. Y Y. l

8; A process for recovery of valuable products from spent doctor solutions resulting from the treatment of hydrocarbon'. oils which comprises separating the sludge Vfrom the spent solution, weathering said sludge by exposure to sunlight and Weather conditions Yfor a suicienttime to lconvert thev sludge into a'weathered sludge containing a substantial amount of an alkali soluble portion and a granular insoluble portion, dis-` solving the soluble portionin Vcaustic alkali to produce a doctor solutionand suspending the insoluble granular portion in caustic alkali to produceY a suspensionfor sweetening hydrocar-f bon oils. y

i 9. In arprocess for the treatment of hydrocarbon oils in which a light hydrocarbon oil is sweetened with a doctor solution in a doctorV treating operation and a sweetened oil and a suspension of lead sludge are 'separately withdrawn, the steps of weathering said sludge by exposure `to sunlight and varying weather conditions in an earthen pit to convert alkali insoluble to alkali soluble lead compounds, dissolving the soluble lead compounds in caustic soda to produce a Ydoctor solution forreuse in said treatin'g operation. l n

l0; In a process for the treatment of hydrocarbon oils in which one;hydrocarbon oilis sweet' ened with a doctor solution in a doctortreating operation and a sweetened oil and a suspension of lead sludge are 'separately withdrawn, thesteps of weathering said sludge by exposure to sunlight and varying weather conditions in a weathering basin to convert the lead sludgel to an alkali soluble portion and a granular insoluble portion, dissolving the soluble portion lin aqueous causticsoda for reuse in said doctor treating operation,

and suspending the granular Vinsoluble portion I phere in a weatheringV basin, withdrawing weathl vered sludge from said b-asin and mixing it with vsaid suspension to produce a treating agent for .hydrocarbon oils.`

. BYRON F. DOOLEY, JR. 

